Modern calculators are capable of numerous mathematical functions. Many calculators are hand-held and thus have limited space for a display and keyboard. A design tension thus exists between increasing the functionality of a calculator and the limited space for buttons on the keyboard and the display. Some calculators have multiple functions assigned to each button. However, multiple function assignments to a single button can be burdensome on the user of the calculator. At any rate, even with multiple function assignments for each button, there still might not be enough button space for all of the functions desired.